Raillietina cesticillus infection causes reduced egg production in chickens in a windowless poultry house.

In a windowless poultry house raising layer chickens in Kanagawa prefecture, Japan, a slight increase in the mortality of chickens and a decrease in egg production were observed. Necropsy revealed numerous tapeworms and proglottids in chicken intestines. Histopathologically, gut-associated lymphoid tissues were observed in the lamina propria of the jejunum; however, no significant changes were observed in the other organs. Numerous hide beetles, Dermestes maculatus DeGeer, intermediate hosts of Raillietina cesticillus, were observed in the poultry house. Following a decline in beetle numbers, egg production increased and chicken mortality decreased. The life cycle of a tapeworm was easily established in a closed space, such as a windowless house, which led to severe infections.

Molecular detection of three intestinal cestode species (Raillietina echinobothrida, R. tetragona, R. cesticillus) from poultry in Thailand.

Cestodes belonging to the genus Raillietina are a major veterinary health problem affecting the poultry industry, particularly chickens (Gallus gallus domesticus) and ducks (Anas playtrhynchos domesticus). The traditional method for accurately detecting this cestode based on their morphological characteristics is rather difficult due to the large number of morphological similarities. Consequently, this study aimed to develop specific primers for R. echinobothrida, R. tetragona, and R. cesticillus detection that could be used to indicate epidemic areas for protection and infection control. Specific primers were manually designed based on the internal transcribed spacer 2 region and validated, establishing the optimal temperature, final concentration in PCR mixture, specificity, and sensitivity of each primer set. The results showed that the primers amplify specific species without cross-amplifying other parasites and hosts. The PCR products were about 473, 352, and 397 bp long for R. echinobothrida, R. tetragona, and R. cesticillus, respectively. The sensitivity test demonstrated that R. echinobothrida and R. cesticillus-specific primers detect a minimum of 5×10-2 ng DNA, while R. tetragona-specific primers detect a minimum of 0.5 ng genomic DNA. The specific primers successfully developed in this study might be useful for detecting cysticercoids in intermediate hosts or adult stages in poultry for epidemiological surveys, management and control of infection.RESEARCH HIGHLIGHTS This study established specific primers for Raillietina species detection.The ITS2 region is an effective molecular marker for Raillietina identification.

Morphology and Molecular Phylogeny of Raillietina spp. (Cestoda: Cyclophyllidea: Davaineidae) from Domestic Chickens in Thailand.

Raillietina species are prevalent in domestic chickens (Gallus gallus domesticus) in Phayao province, northern Thailand. Their infection may cause disease and death, which affects the public health and economic situation in chicken farms. The identification of Raillietina has been based on morphology and molecular analysis. In this study, morphological observations using light (LM) and scanning electron microscopies (SEM) coupled with molecular analysis of the internal transcribed spacer 2 (ITS2) region and the nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) gene were employed for precise identification and phylogenetic relationship studies of Raillietina spp. Four Raillietina species, including R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp., were recovered in domestic chickens from 4 districts in Phayao province, Thailand. LM and SEM observations revealed differences in the morphology of the scolex, position of the genital pore, number of eggs per egg capsule, and rostellar opening surface structures in all 4 species. Phylogenetic relationships were found among the phylogenetic trees obtained by the maximum likelihood and distance-based neighbor-joining methods. ITS2 and ND1 sequence data recorded from Raillietina sp. appeared to be monophyletic. The query sequences of R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp. were separated according to the different morphological characters. This study confirmed that morphological studies combined with molecular analyses can differentiate related species within the genus Raillietina in Thailand.

Morphology and Molecular Phylogeny of Raillietina spp. (Cestoda: Cyclophyllidea: Davaineidae) from Domestic Chickens in Thailand

Raillietina species are prevalent in domestic chickens (Gallus gallus domesticus) in Phayao province, northern Thailand. Their infection may cause disease and death, which affects the public health and economic situation in chicken farms. The identification of Raillietina has been based on morphology and molecular analysis. In this study, morphological observations using light (LM) and scanning electron microscopies (SEM) coupled with molecular analysis of the internal transcribed spacer 2 (ITS2) region and the nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) gene were employed for precise identification and phylogenetic relationship studies of Raillietina spp. Four Raillietina species, including R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp., were recovered in domestic chickens from 4 districts in Phayao province, Thailand. LM and SEM observations revealed differences in the morphology of the scolex, position of the genital pore, number of eggs per egg capsule, and rostellar opening surface structures in all 4 species. Phylogenetic relationships were found among the phylogenetic trees obtained by the maximum likelihood and distance-based neighbor-joining methods. ITS2 and ND1 sequence data recorded from Raillietina sp. appeared to be monophyletic. The query sequences of R. echinobothrida, R. tetragona, R. cesticillus, and Raillietina sp. were separated according to the different morphological characters. This study confirmed that morphological studies combined with molecular analyses can differentiate related species within the genus Raillietina in Thailand.

Ground beetle, Opatroides frater (Coleoptera) as natural intermediate host for the poultry tapeworm, Raillietina cesticillus.

Poultry farms in and around Namakkal with a history of tapeworm infection were surveyed for the presence of beetles which could act as intermediate host for the tapeworms. Beetles collected from different poultry farms with suspected tapeworm infection were examined for the presence of metacestode stage of the parasite. A total of 1,880 beetles were collected from 12 poultry farms with suspected tapeworm infection to study the vector potentiality. Out of these, 205 beetles (10.9 %) from nine farms were found to harbour cysticercoids. The percentage of cysticercoid infection in beetles was 8.24, 10.34 and 16.66 % respectively in three different surveys. The beetles harbouring the cysticercoids were identified as Opatroides frater, which may be a natural intermediate host for Raillietina cesticillus. Infection free young chicks (4 weeks old) were experimentally infected with specific number of cysticercoids and prepatent period of tapeworms was found to be between 12 and 13 days. Gravid segments were expelled between 3 and 4 p.m. consistently. The results of this study would help to formulate suitable control measures against the above tapeworm infection.